Symbian
Symbian OS Library

SYMBIAN OS V9.3

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Location: LineBreak.h
Link against: linebreak.lib

Class MLineBreaker

class MLineBreaker;

Description

Customizes the Unicode line-breaking algorithm.

Members

Defined in MLineBreaker:
EAiLineBreakClass, EAlLineBreakClass, EB2LineBreakClass, EBaLineBreakClass, EBbLineBreakClass, EBkLineBreakClass, ECbLineBreakClass, EClLineBreakClass, ECmLineBreakClass, ECrLineBreakClass, EExLineBreakClass, EGlLineBreakClass, EHyLineBreakClass, EIdLineBreakClass, EInLineBreakClass, EIsLineBreakClass, ELfLineBreakClass, ELineBreakClasses, ENsLineBreakClass, ENuLineBreakClass, EOpLineBreakClass, EPoLineBreakClass, EPrLineBreakClass, EQuLineBreakClass, ESaLineBreakClass, ESgLineBreakClass, ESpLineBreakClass, ESyLineBreakClass, EXxLineBreakClass, EZwLineBreakClass, ExtendedInterface(), GetLineBreak(), GetLineBreakInContext(), GetLineBreakL(), IsHangingCharacter(), LineBreakClass(), LineBreakPossible(), anonymous

Member functions

LineBreakClass()

virtual IMPORT_C TUint LineBreakClass(TUint aCode, TUint &aRangeStart, TUint &aRangeEnd) const;

Description

Converts Unicode character into line breaking class.

Parameters

TUint aCode

Input Unicode value.

TUint &aRangeStart

Returns the start of the contiguous range of characters including aCode that have the returned line breaking class.

TUint &aRangeEnd

Returns the end of the contiguous range of characters including aCode that have the returned line breaking class.

Return value

TUint

The line breaking class for aCode.

LineBreakPossible()

virtual IMPORT_C TBool LineBreakPossible(TUint aPrevClass, TUint aNextClass, TBool aHaveSpaces) const;

Description

Returns whether line breaks are legal between a character of line breaking class aPrevClass and aNextClass, with intervening spaces or not as determined by aHaveSpaces.

Parameters

TUint aPrevClass

The class before the potential line break.

TUint aNextClass

The class after the potential line break.

TBool aHaveSpaces

Whether spaces separate the characters.

Return value

TBool

ETrue if and only if a line break is legal in the situation described.

GetLineBreakInContext()

virtual IMPORT_C TBool GetLineBreakInContext(const TDesC16 &aText, TInt aMinBreakPos, TInt aMaxBreakPos, TBool aForwards, TInt &aBreakPos) const;

Description

Returns whether a line break is possible within a run of characters all having the class ESaLineBreakClass (Complex content). Languages with Unicocde characters having such a class include: Thai, Lao, Myanmar and Khmer. This default implementation of the GetLineBreakInContext() method only supports the Thai script. Breaks are determined in Thai based on a simple understanding of syllable boundaries. When characters from the other unsupported Sa class languages are found the method exits with EFalse.

Parameters

const TDesC16 &aText

The text to be searched, which is a contiguous run of characters of class SA (or CM attatched to SA). The break position may be restricted further by aMinBreakPos and aMaxBreakPos, but more text is provided for extra context should it be needed.

TInt aMinBreakPos

The start of the text to be considered for line breaks.

TInt aMaxBreakPos

The end of the text to be considered for line breaks.

TBool aForwards

ETrue if aBreakPos is to be set with the first legal break position, EFalse if aBreakPos is to be set with the last legal break position.

TInt &aBreakPos

If break position found on exit its value is >= Min and <= Max positions supplied.

Return value

TBool

TBool ETrue if and only if a legal break was found, EFalse otherwise.

IsHangingCharacter()

virtual IMPORT_C TBool IsHangingCharacter(TUint aChar) const;

Description

Returns ETrue if the character value may be positioned outside the margins.

Parameters

TUint aChar

Chatacter to test

Return value

TBool

ETrue if the character value may be positioned outside the margins.

GetLineBreak()

IMPORT_C TBool GetLineBreak(const TDesC16 &aText, TInt aMinBreakPos, TInt aMaxBreakPos, TBool aForwards, MContingentLineBreaker *aCbDelegate, TInt &aBreakPos, TInt &aBreakPosAfterSpaces) const;

Description

Parameters

const TDesC16 &aText

TInt aMinBreakPos

TInt aMaxBreakPos

TBool aForwards

MContingentLineBreaker *aCbDelegate

TInt &aBreakPos

TInt &aBreakPosAfterSpaces

Return value

TBool

GetLineBreakL()

IMPORT_C TBool GetLineBreakL(const TDesC16 &aText, TInt aMinBreakPos, TInt aMaxBreakPos, TBool aForwards, MContingentLineBreakerL *aCbDelegate, TInt &aBreakPos, TInt &aBreakPosAfterSpaces) const;

Description

Parameters

const TDesC16 &aText

TInt aMinBreakPos

TInt aMaxBreakPos

TBool aForwards

MContingentLineBreakerL *aCbDelegate

TInt &aBreakPos

TInt &aBreakPosAfterSpaces

Return value

TBool

ExtendedInterface()

virtual IMPORT_C void *ExtendedInterface(TUid &aUid) const;

Description

Returns an interface to more functions, or 0 if these are unsupported. Currently there are no other functions, so 0 is always returned. If this function is overridden, it must base call if aUid is not recognised, rather than just returning 0.

Parameters

TUid &aUid

Identifies the interface to be returned.

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Member enumerations

Enum anonymous

n/a

Description

The Unicode line breaking classes; see Unicode Technical Report 14. Not a named enumerated type, so that overriding classes may add new line breaking classes freely. The description of each constant gives the name of the line-breaking class, an example and a brief, imprecise description of the default behaviour of characters of that class.

EOpLineBreakClass

Opening Punctuation (e.g. '['). Breaking after prohibited.

EClLineBreakClass

Closing Punctuation (e.g. ']'). Breaking before prohibited.

EQuLineBreakClass

Ambiguous Quotes (e.g. '"'). Breaking before and after prohibited.

EGlLineBreakClass

Glue (e.g. Non-breaking space). Breaking before and after prohibited unless spaces are present.

ENsLineBreakClass

Non-Starter (e.g. small Japanese kana). Breaking before prohibited if no spaces present.

EExLineBreakClass

Exclamation or Interrogation (e.g. '?'). Like closing punctuation except before Postfix or Non-starter.

ESyLineBreakClass

Symbol (e.g. '/'. Like Alphabetic, but allows breaking before Alphabetic.

EIsLineBreakClass

Numeric Infix Separator (e.g. ','). Forbids breaking after any and before Numeric.

EPrLineBreakClass

Numeric Prefix (e.g. '$'). Forbids breaking before Numeric.

EPoLineBreakClass

Numeric Postfix (e.g. '%'). Forbids breaking after Numeric.

ENuLineBreakClass

Numeric (e.g. '1').

EAlLineBreakClass

Alphabetic (e.g. 'a').

EIdLineBreakClass

Ideographic (e.g. Japanese Kanji). Generally break before or after

EInLineBreakClass

Inseparable (e.g. ellipsis). Forbid breaks between Inseparables.

EHyLineBreakClass

Hyphen (e.g. '-'). Allows a break after except before Numeric.

EBaLineBreakClass

Break After. Generally allow a break after. Breaking between Break Afters not separated by spaces is prohibited.

EBbLineBreakClass

Break Before. Generally allow a break before. Breaking between Break Befores not separated by spaces is prohibited.

EB2LineBreakClass

Break Before and After. Generally allow a break before or after. Breaking between Break Before and Afters is prohibited, even if spaces are present.

EZwLineBreakClass

Zero-Width Space. Allow a break.

ECmLineBreakClass

Combining Mark. Takes on the class of its base class.

EBkLineBreakClass

Mandatory Break.

ECrLineBreakClass

Carriage Return. Break after unless part of a CRLF pair.

ELfLineBreakClass

Line Feed. Break after.

ESgLineBreakClass

Surrogate. Half of a surrogate pair.

ECbLineBreakClass

Contingent Break (e.g. embedded pictures). Uses external information

ESpLineBreakClass

Space. Intervening characters of class Space are indicated by aHaveSpaces in LineBreakPossible.

ESaLineBreakClass

Complex Context (e.g. Thai). Runs of Complex Context are passed to GetLineBreakInContext.

EAiLineBreakClass

Ambiguous. Characters of ambiguous East Asian width are treated as Alphabetic, unless they are resolved as being "Wide", in which case they are treated as Ideographic.

EXxLineBreakClass

The Xx class is used when the class is unknown; e.g.; outside the provided context.

ELineBreakClasses

The number of Unicode line break classes.

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